We are asked to determine the frequency of an open air column. To do that we will use the following formula:

Where:

Substituting the values:

Solving the operations we get:

Therefore, the first frequency is 170 Hz.
To determine the second frequency we use the following formula:

Substituting the values we get:

Solving the operation we get:

Therefore, the second frequency is 340 Hz.
We notice that the relationship between frequency is:
